When a telephone call is made from a telephone by its user, the telephone signals a call-processing switch, or similar equipment such as a server, that a request is being made to set up the call. The call-processing switch handles the request, which comprises dialing information that includes the dialed digits of the called telephone number; historically, the switch detected and analyzed each digit as it was dialed. Although the telephone participates in the call-setup process, it is the call-processing switch that has typically performed the majority of the call-setup processing between the two devices.
Plain Old Telephone Service (or “POTS”) telephones have evolved into intelligent, telecommunications endpoint devices. These endpoints support more high-level signaling, such as the Session Initiation Protocol (or “SIP”) and H.323 protocol, to initiate calls or to activate features—in contrast to the low-level, stimulus-based signaling that is traditionally associated with POTS telephony. These smarter endpoints can even establish calls with limited, if any, assistance from a call-processing server. To establish calls, when working with a server such as an Internet Protocol-based, private branch exchange (IP-PBX), the endpoint device stores certain aspects of the server's configuration, such as the “dialing plan.”
The term “dialing plan,” and its inflected forms, is defined for use in this Specification, including the appended claims, as a call-control scheme that establishes the expected pattern and number of digits for a telephone number. This includes country codes, access codes, area codes, and various combinations of digits dialed. For instance, the North American Public Switched Telephone Network (PSTN) uses a 10-digit dialing plan that includes a 3-digit area code and a 7-digit telephone number. Most private branch exchanges (PBX) support variable-length dialing plan plans that use 3 to 11 digits that may be preceded by a “9” if required to access an outside line. A dialing plan comprises at least one alphanumeric string that represents at least a part of a call-control rule. A dialing plan is also referred to as a “dial plan” or “dialplan.”
Dialing plans aside, as the telecommunications endpoints continue to evolve, so do the demands on the network for new features, both on the endpoints and on the call-processing servers. The call-processing servers also have to deal with the trend of increased mobility, in which each telecommunications system user is often able to log in to multiple endpoints and where each endpoint can be used by multiple users at various times.